Coral Reef Destruction

Ten percent of the world's reefs have been completely destroyed. In the Philippines, where coral reef destruction is the worst, over 70% have been destroyed and only 5% can be said to be in good condition because of the very little clear water. What has happened to destroy so many reefs? 

There are two different ways in which humans have contributed to the destruction of the Earth's coral reefs, indirectly and directly. Indirectly, we have destroyed their environment. As you read earlier, coral reefs can live only in very clear water. The large population centers near coasts has led to silting of reefs, pollution by nutrients that lead to algal growth that smothers the coral, and overfishing that has led to increase in number of predators that eat corals.

Warming of the ocean causes corals to sicken and die. Even a rise of one degree in the average water temperature can hurt the coral. Due to global warming, 1998 was the hottest year in the last six centuries and 1998 was the worst year for coral.The most obvious sign that coral is sick is coral bleaching. That is when either the algae inside die, or the algae leave the coral. The algae are what give coral its color, so without the algae the coral has no color and the white of the limestone shell shines through the transparent coral bodies. People have been noticing coral bleaching since the turn of the century, but only since the 1980s has it gotten really bad.

For more,go to: http://oceanworld.tamu.edu/students/coral/coral5.htm